The present invention relates to physical separation of minerals and in particular to the separation of minerals of different mineralogical character.
Valuable minerals in ores are commonly present as more than one type of mineral. The types of minerals can range from sulphides e.g. pyrite, chalcocite, pentlandite etc. to oxide such as cuprite, tenorite, smithsonite, zincite.
Each of these minerals can exhibit quite different flotabilities. If one applies a particular flotation process to such a mixed mineral ore, one may obtain partial recovery of the valuable minerals, but a proportion of the valuable mineral or indeed another valuable mineral may be lost. The prior art does not adequately address or provide a process for recovery of the various types of valuable minerals in a mixed mineral ore.
The present invention seeks to overcome at least some of the problems of the prior art or at least provide a commercial alternative thereto.
In a first aspect, the present invention provides a process for recovery of valuable minerals of different mineralogical character from an ore wherein
a milled slurry or flotation concentrate is subjected to a first conditioning step followed by first flotation step to recover a valuable mineral in the slurry or concentrate is recovered,
a tailings stream from the first flotation step being subjected to a second conditioning step followed by a second flotation step to recover any valuable mineral in the tailings stream, wherein
one of the conditioning steps includes conditioning the slurry or flotation concentrate with an oxidising gas containing a gas selected from the group consisting of oxygen and ozone, and
the other of the conditioning steps includes conditioning the slurry or flotation concentrate with a substantially non-oxidising gas and an oxidisable surface modifying reagent.
In a preferred embodiment, the oxidative conditioning step is conducted first, followed by flotation, and the conditioning step with an inert or non-oxidising gas is conducted second, followed by the appropriate flotation step.
The present invention is suitable for an ore containing a mixture of valuable minerals including sulphidic minerals or non-sulphidic and sulphidic minerals, and non-valuable sulphidic minerals and non-valuable xe2x80x9cganguexe2x80x9d material.
Suitable oxidising gases include oxygen, oxygen enriched air and/or ozone. Suitable inert or non-oxidising gases include nitrogen, argon, carbon dioxide, sulfur dioxide or admixtures thereof.
Which oxidisable surface modifying reagents are used will depend on the desired mineral separation and can be chosen as appropriate from either the group containing sodium hydrosulphide, sodium sulphide, hydrogen sulphide, ammonium sulphide, ammonium hydrosulphide or the group containing sulfoxy agents including sodium sulphite, sodium hydrogen sulphite, sodium metabisulphite, sodium bisulphite, sulfur dioxide gas or solution, sulphite agents, K, Ca, NH4+ salts thereof.